Presently known fixed flat plate type solar collectors that are built at the job site are so firmly attached to or integrated into the support structure in such a way that they fail to provide for a satisfactory differential thermal expansion between the collector and the underlying support structure. Such rigidity of attachment results in leakage. Presently known modular factory built type solar collectors have the disadvantages of unnecessary duplication of materials and the use of relatively expensive materials.
Attempts have been made to save materials by the use of flat plate collectors as a cover for the underlying structure but presently known collectors of this type rigidly affix some part to the rafters or equivalent support structures and thereby do not allow for differential expansion between the collector and underlying structure. In particular, in the prior art the cover is rigidly affixed to the top of the rafters and the collector plate and underlying fluid flow pan are recessed below the rafters. This arrangement demonstrates an inability to maintain the integrity of the weather membrane, is difficult to service, and has reduced the area behind the collector plate that is available for insulation.
Moreover, known solar collectors that are of the modular type are built in a factory location remote from the point of use. The apparatus of the present invention is particularly suited for being fabricated at the job site, thereby affording a number of advantages over factory built modules and presently known site built systems. These advantages include an ability to expand and contract relative to the support structure, an assembly that is tailored to fit the structure on which it is mounted, and a high degree of quality control.